1. Field of the Invention
The present disclosure relates to diagnosis of disease and measurement of homeostatic status from a sample of whole blood. More specifically, the present disclosure relates to the field of characterizing RNA that is contained in vesicles from whole blood to diagnose disease.
2. Description of Related Art
In many cases, physicians interpret a patient's symptoms, medical history and the results of a physical exam to derive an initial diagnosis. Medical tests are an integral part of confirming or modifying an initial diagnosis. Such tests may include a range of different tests, from simple, non-invasive tests such as blood pressure measurements, monitoring the patient's temperature, medical imaging (e.g., x-rays), to minimally invasive tests such as, for example, blood tests, to more invasive tissue biopsies and even in-patient surgical biopsies. Much of the decision tree that directs which tests are performed are based on the clarity of the symptoms experienced by the patient, the physical exam, and the information gained by non- or minimally-invasive diagnostic tests. However, some diseases are difficult to diagnose, possibly because of vague, inconsistent, or overly common symptoms and therefore require a more invasive and/or directed diagnostic approach.
Currently, some diagnostic medical tests are performed on blood extracted from a patient to diagnose a disease from a biochemical pattern that is not present in healthy patients or is altered from a previously obtained patient sample. These tests commonly utilize plasma or serum and measure, for example electrolytes, urea, creatinine, and glucose, among other analytes. Other tests measure plasma proteins such as albumins, immunoglobulins, fibrinogens, and regulatory proteins. Some tests measure other biological compounds, such as, for example, thiamin, riboflavin, niacin, vitamin B6, folic acid, vitamin D, biotin, iron, and clotting factors factor V and factor X.
However, these diagnostic tests are typically based upon the presence of known and well characterized markers in the blood. For instance, diagnostic tests for HIV infection detect antibodies in the blood of a patient. However, there is a window soon after infection where the immune system has not yet generated antibodies and the levels of disease-associated marker proteins are minimal, making detection difficult. In some circumstances, the use of an antibody based test, such as an ELISA or a western blot, may not be feasible because it may not be possible to generate antibodies with adequate affinity or avidity for their target protein. The target antigen or protein may also change conformation or be unstable when taken out of the body. Moreover, antibodies may bind to other (non-target) proteins non-specifically. Additionally, certain diagnostic tests employ chemical reactions (e.g., colorimetric changes) to identify markers from blood or other fluid samples. Such tests may also be affected by similar limitations as are described above (e.g., reliance on known reactants, sensitivity, etc.). Thus, there exists a need for a sensitive, accurate and reproducible diagnostic test for a variety of diseases that allows for early detection and/or diagnosis of a disease.